I've found plenty of load-time benefit by loading my plugin classes (subactors) dynamically, but *without* packaging them as external libraries.
E.g create a subfolder in your project called "plugins" containing all your subactor libraries. Then just drop the plugins folder into the "Always Included" section of your build spec. Load as needed dynamically by path from "..myapp.exe\plugins\mysubactor..".
Provided you don't have any static links to your subactors in your main code then your app should load up much quicker. Only drawback is that you need to re-release the build if you change any single plugin, but often that is no problem in practice.